In situ epitaxial MgB(2) thin films for superconducting electronics

• Published in: Nature materials Vol. 1; no. 1; pp. 35 - 38
• Main Authors: Zeng, Xianghui, Pogrebnyakov, Alexej V, Kotcharov, Armen, Jones, James E, Xi, X X, Lysczek, Eric M, Redwing, Joan M, Xu, Shengyong, Li, Qi, Lettieri, James, Schlom, Darrell G, Tian, Wei, Pan, Xiaoqing, Liu, Zi-Kui
• Format: Journal Article
• Language: English
• Published: 01-09-2002
• ISSN: 1476-1122
• DOI: 10.1038/nmat703

The newly discovered 39-K superconductor MgB(2) holds great promise for superconducting electronics. Like the conventional superconductor Nb, MgB(2) is a phonon-mediated superconductor, with a relatively long coherence length. These properties make the prospect of fabricating reproducible uniform Josephson junctions, the fundamental element of superconducting circuits, much more favourable for MgB(2) than for high-temperature superconductors. The higher transition temperature and larger energy gap of MgB(2) promise higher operating temperatures and potentially higher speeds than Nb-based integrated circuits. However, success in MgB(2) Josephson junctions has been limited because of the lack of an adequate thin-film technology. Because a superconducting integrated circuit uses a multilayer of superconducting, insulating and resistive films, an in situ process in which MgB(2) is formed directly on the substrate is desirable. Here we show that this can be achieved by hybrid physical-chemical vapour deposition. The epitaxially grown MgB(2) films show a high transition temperature and low resistivity, comparable to the best bulk samples, and their surfaces are smooth. This advance removes a major barrier for superconducting electronics using MgB(2).